This invention relates to a delivery device.
Minimal access surgery (MAS) allows certain operations to be carried out through small access holes thus avoiding the creation of large traumatic wounds. However difficulties arise in suturing surgical incisions and ligating inside the patient using current instruments due to the small size of the access hole which restricts movement of the instrument. Tying knots in suture and ligating threads is particularly difficult and time consuming.
In an attempt to overcome this problem, devices have evolved for manipulating needles within the body. One such device (disclosed in WO92/05828) comprises a cannula which may be inserted into the body through a narrow opening. The cannula houses a piston which is slidable within the cannula and manipulates a needle. The needle is retained inside the cannula during insertion of the cannula into the patient. The needle is formed from elastic material and when retained inside the cannula, the needle is held in a generally straightened configuration. When the cannula is in place, the needle can then be projected from the end of the cannula to penetrate tissues and join wounds. Other items such as ring clips can be manipulated using the device. Several needles cane stored in the device in a straightened configuration. In such a configuration the needle s exert a force on the device in an attempt to reform to their unstressed configuration. This causes difficulty in moving the needles within the device.
According to the present invention there is provided a device for the delivery of a shape memory securing member in minimal access surgery, the device having an exit for the securing member and means to move the securing member through the exit, the device further including a magazine having a plurality of channels each of which can store a securing member.
Preferably, each securing member is restrained in the device in a first configuration, and upon passing through the exit adopts a second configuration. Also preferably, each channel is separately alignable with the exit.
One preferred form of magazine is a barrel. The barrel may be rotatable around an axis and the channels may be disposed parallel to said axis or may lie in a helical configuration. This arrangement can be likened to a xe2x80x9crevolver barrelxe2x80x9d on a firearm.
The first configuration in which the securing members are held inside the device is optionally straight. However, the securing members may be held in the device in a generally helical configuration. This partially relaxes the securing members and allows the use of high curvature securing members which cannot easily adopt a straightened configuration. The high curvature securing members can form tighter coils when they pass through the exit of the device.
Preferably, the second configuration is the form of a coil or loop. The coils may be overlapping (like a key ring) or may be partially open. The second configuration is preferentially adopted by the securing member in the absence of any other force. The loops of the second configuration may be round or some other shape such as a rounded oblong or a round cornered triangle. On leaving the device the securing member automatically adopts the second configuration, which is the preferred shape according to the shape memory of the member.
The channels may include or be in the form of tubes which may themselves move within the device. The securing members may be housed within the tubes. The means to move the securing members may act upon the securing members direct or upon the tubes, to move a tube and a securing member housed therein towards the exit.
When the securing members are stored within tubes, the tubes can be manipulated within the device more easily than the securing members alone. The tubes may be stored in parallel in the barrel, or may be stored sequentially in a line. The exit of the device may be so arranged as to contain the tubes but allow the securing members to pass from the tubes through the exit.
The magazine may have indexing means to align a securing member with the exit or with a second channel communicating with the exit. The indexing means may also align the securing member with the means for moving the securing member.
The magazine may also comprise other means of storing the securing members, such that the securing members are sequentially arranged in a column, line, row or helix, and are sequentially moved to the exit.
The magazine may be a replaceable element and may contain only sutures or ligatures or a selection of both, optionally in a defined order. The magazine(s) may be colour-coded for ease of use.
The means for moving the securing members may be disposed between the exit and the securing members, such that the securing members are pulled towards the exit, or alternatively, the securing members may be disposed between the exit and the means for moving the securing members, such that they are pushed towards the exit. In the first arrangement, the means for moving the securing members may comprise an inch worm motor or pinch wheel.
The exit of the device preferably comprises a tube which is curved in more than one plane optionally, the tube is curved once or twice to lie in two or three planes respectively and the exit is located at the end of the tube. The tube may be of circular cross-section or may be of a different cross-section, such as rectangular or oval.
The exit tube may be sharpened so that it can penetrate tissue before the movement of the securing members through the exit. This may be desirable where the securing members do not easily penetrate the tissue surface. Where tissue penetration by an exit tube is undesirable, the exit tube may be replaced by a tube with a wide or bulbous end. The tube may be part of a detachable assembly that allows re-orientation or extension of the assembly. The assembly can be interchangeable with other forms of assembly to allow the use of e.g., left and right hand forms and straight forms.
In an alternative form of the instrument, the exit may be embedded in a more substantial member such as a half-round continuation of the main intrument body. One or more clamping jaws acting in opposition to the exit (or its more substantial containment structure) may be incorporated in order that it can easily be penetrated by the sutures. The device than has dual suturing and grasping functions. There may be two moving jaws, one behind the other, so that two connective folds of tissue may be grasped for suturing together. Each jaw would have a cutaway to allow passage of the suture. The jaw(s) may be activated from the handle by concentric connections on the instrument axis or in the form of external tubes.
In another embodiment of the invention, an ultrasonic transducer may be incorporated in or near the exit. This may be used to excite vibrations in the suture in order to make it penetrate tissue more readily.
In some embodiments, joints between (for example) exit tubes and other tubes in the device may be in the form of collars, where one tube end fits within an end of another tube. This allows the securing members to be moved past joints between tubes more easily. Preferably, the inner faces of all tubes used are smooth.
The securing members are preferably formed from shape memory alloy such as nickel-titanium (NiTi) alloy and may comprise elongate strips of said alloy which are coiled in the absence of any deforming force. The securing members could also be formed from stainless steel, from another biocompatible material (or coated material) or from material which is resorbable by the body.
The securing members may be in the form of sutures which have at least one sharp end or may be in the form of ligatures having blunt ends. In the case of the ligature, the surgeon holds the exit of the device next to the body part to be ligated (e,g., a blood vessel) and the ligature will wrap itself around the body part as it is expelled. Securing members in the form of sutures are formed with a sharp point at the leading end. The surgeon then places the device so that the point of the exiting sutures penetrates the tissue(s) to be sutured. The suture then re-coils upon exit and creates a join in the tissue(s). Also in the case of a suture, the exit tube may be required to deliver the suture in a plane normal to the axis of the instrument.
A further advantage of the delivery device according to one embodiment of the present invention is that it can store several sutures or ligatures to allow multiple placements without the need to withdraw the instrument from the patient.
According to a second aspect of the present invention there is provided a device for the delivery of a shape memory securing member in minimal access surgery, the device having an exit for the securing member, means to move the securing member through the exit, and means for cutting the securing member, preferably once a portion thereof has been passed through the exit.
Preferably, upon leaving the device, the expelled portion of the securing member automatically adopts a configuration in accordance with its shape memory.
The device according to the second aspect of the invention preferably contains a securing member in a continuous form, such as a roll, helix or coil. The configuration of the securing member preferably changes as it passes between the interior and exterior of the device. Thus when the securing member is in the form of a high-curvature coil of shape memory alloy, it can be maintained in a relaxed state (at or near its preferred shape according to its memory) when stored within the device, and need only be subjected to stress when its configuration changes upon leaving the device.
The means for cutting the securing member is preferably disposed adjacent the exit so as to cut the securing member as it leaves the device. The means for cutting and the means for expelling may be provided by a single element, for example, a pinch wheel. The means for cutting may include means for sharpening the end of the securing member left inside the device.
The present invention further provides a shape memory securing member for use in a device as defined above, the securing member having the form of a loop, coil or a helix in the absence of any force acting upon it.